The dedicated metallic return conductor (DMR) of an HVDC transmission line may flashover as a consequence of a pole insulation failure or backflash over simultaneously with a pole during a lightning-induced event. The transient voltage surges induced on the DMR of the Quebec-New England HVDC intertie by pole faults are analyzed, and the sensitivity of simultaneous pole and DMR backflashover probab...
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Previous studies have shown that many types of system disturbances will lead to commutation failure at HVDC inverter stations. The problem is further aggravated if the inverter is connected to a weak (low short-circuit ratio) AC system. The authors analyze the problem in terms of the frequency spectrum of the AC network and its relation to the transient disturbance which causes the failure. Method...
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A 150 MVA reactor current interruption test using a GIS (gas-insulated switchgear) on an actual 275 kV cable system and a laboratory high-frequency current interruption test using a 300 kV SF 6 gas circuit breaker were conducted. The results of these tests and their analyses, made simultaneously, permitted (1) the calculation of reignition surges and the detection of high-frequency arc ...
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Heat-shrinkable materials have become widely established as a way of providing joints and termination for distribution class cables. The technology has been extended to develop a joint for 69 kV cables. Simple components and a special connector were developed to create a slim profile joint that is easy to install. The design overcomes some problem areas for polymeric cables-water ingress, insulati...
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The application of SVCs (static volt-ampere reactive compensators) to distribution systems to solve voltage fluctuation problems is discussed. Fast and repetitive voltage fluctuations can exist on an electric utility's distribution system. These voltage fluctuations, which are usually caused by motor-starting or other pulsating or irregular loads such as welders, can be objectionable and can pose ...
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Different analytical methods that may be used to calculate values of temporary overvoltage on multigrounded distribution systems as a result of single line-to-ground faults are evaluated in terms of their general accuracy; their ability to account for changes of earth resistivity, ground electrode resistances, and grounding frequency; and the overall impact of such changes on the calculated overvo...
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The authors describe the design[, assembly[, and testing results for prototypes of an optical current transformer (CT) and a voltage-dividing-type voltage transformer (PD). The optical CT and PD were developed to be applicable to three-phase enclosed-type 300 kV gas-insulated switchgear (GIS) and air-insulated 168 kV substation systems. Test results for the newly developed optical CT and PD showed...
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The results of puncture breakdown tests on rubber gloves are presented. A positive polarity switching surge voltage (275/2500 μs) or a 60 H alternating voltage was applied to the glove to cause breakdown. The effect of mechanical pressure on glove breakdown behavior and the influence of using a leather protector were investigated. It was found that protected gloves are more likely to break down...
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Discharges originating from laboratory upward leaders are studied experimentally with a configuration consisting of two parallel vertical rods at ground and an elevated plane. The flashover probability of each rod, the effect of gap configuration on that probability, and the shielding effect of the taller rod on the smaller one are investigated. Experimental results are analyzed, taking into accou...
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Seven types of commercially available distribution composite insulators with sheds made of EPR (ethylene-propylene rubber) or epoxy resin were subjected to various functional aging tests recommended by the IEC or the IEEE. The influence of ultraviolet (UV) radiation on the aging of the shed materials was also evaluated. The usefulness of the various aging and diagnostic tests is discussed, and a m...
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An algorithm for optimizing shunt capacitor sizes on radial distribution lines with nonsinusoidal substation voltages such that the RMS voltages and their corresponding total harmonic distortion lie within prescribed values is presented. The problem is formulated as a combinatorial optimization problem with inequality constraints. A simple heuristic numerical algorithm that is based on the method ...
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New EHV XLPE (extremely high-voltage cross-linked polyethylene) cable technologies have been developed and applied to commercial service. For example, 66/154 kV XLPE cables are currently used in a new underground transmission network. The number of these cables has rapidly increased and their use has proved very satisfactory. A 275 kV XLPE long-distance underground transmission line with straight-...
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An instrument capable of detecting and locating partial discharge sites and faults in shielded power cables was developed on behalf of a group of US electric utilities. The instrument uses state-of-the-art electronic hardware and advanced digital signal processing techniques. The partial discharge signals are reconstructed using the cable traveling wave characteristics (transfer function), and noi...
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Characterizing the waveshape of voltage and current transients on distribution systems caused by lightning events has been of considerable interest. A solid-state recording device for this purpose was developed in 1984 with high-sample-rate capabilities and the ability to operate for extended periods unattended. One-hundred of these recorders were fabricated and installed on electric utility distr...
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The effects of the many sources of harmonics which occur on distribution systems are discussed and contrasted with the single source of harmonics from a high-impedance ground fault. Field data are presented which show the complexity of modeling the ambient harmonics and the simplicity of the change in the phasor value of the third harmonic which occurs due to a high-impedance ground fault. This ph...
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The fundamentals of inverse time overcurrent relaying, recent changes in transformer characteristic curves, and a flexible microprocessor-based relay that has wide application possibilities are described. Insight into the process of selecting a particular time-current operating characteristic shape for a given application is provided. Guidelines are presented for the selection of a setting for an ...
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High failure rates of equipment resulting in severe operational problems caused the Colorado Springs Dept. of Utilities to investigate switching surge phenomena on their 34.5 kV distribution system. Digital simulations were performed to quantify the magnitude of overvoltages created by such operations as cable switching, capacitor bank switching, and switch restrike in an effort to identify the ca...
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The authors present a methodology for deciding whether or not to implement seismic design modifications at Southern California Edison's (SCEs) substation facilities. The method considers the potential for substation capability loss resulting from earthquake damage, cost of seismic modification made today, the cost of damage restoration after that modification is made, the cost of doing nothing now...
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It is shown that power line carrier (PLC) signal attenuation can be calculated for simple or complex branched networks using a system impedance matrix. Single- and multiple-phase line sections are represented by long line equivalent pi-sections determined at the PLC frequency. The impedance matrix approach can properly represent any complexity of transmission systems including radial lines, tapped...
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Applications of some of the more modern technologies to instruments designed specifically to operate in utility substation environments are described. Particular emphasis is placed on the use of CMOS logic, processor and memory circuits, high-density flexible magnetic disk media, and high-capacity Winchester technology storage devices. The operating history of a number of units over a five-year pe...
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Arrester-protected pole-type distribution transformers were subjected to the combined stresses caused by the conducted steep front impulse and rated 60 Hz voltages. The results are compared with those of similar experiments on unenergized distribution transformers and with low-voltage impulse wave distribution results. It is concluded that (1) tank-mounted direct-connected arresters provide a high...
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Based on the principle of superposition, a novel approach is presented to calculate the electric field in three-core cables so that the electric field problem under any conductor voltage conditions (V Z, VB, VC) can be reduced to a field computation for a basic conductor voltage condition, i.e. VZ=1, VB View full abstract»

A novel lower-cost method of detecting transmission line conductor motion has been developed. The detector is ground based and can be installed by two people with no line outage or physical connection to the transmission line structure. Detection sensitivity is approximately 0.3 m (1 ft) p-p (peak-to-peak). Field testing has shown that the detector can detect several modes of conductor motion, inc...
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A microprocessor-controlled high-voltage current-comparator-based capacitance bridge is described. The bridge has a capacitance ratio and a dissipation factor (loss tangent) measurement range of 1/1 to 100/1 and 0 to 10%, respectively, with a resolution of 1 PPM (part per million). To accommodate capacitance ratios larger than 100/1 (up to 100000/1) and load currents of up to 1000 A, an additional...
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A line-type pulser has been developed to test the effects of steep-front, short-duration (SFSD) pulses on distribution components. The risetime is 50-100 ns and the pulse duration is on the order of 300 ns. Terminators often shattered or punctured rather than flashing over. The insulator flashover voltage is approximately 1.5 times CFO for standard lightning impulses. Arresters exhibit an inductiv...
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Aims & Scope

Installation and operation of apparatus, equipment, structures, materials and systems for the safe, reliable and economic generation, transmission, distribution, conversion, measurement and control of electric energy.